1. Field of the Invention
The present invention relates to a mobile acoustic reproducing apparatus designed to form optimum sound fields at both the driver's seat and the front side passenger's seat by installing loudspeakers at the forward right and left positions and near the middle position of the car compartment.
2. Description of the Prior Art
FIG. 1 is a plan view for explaining a prior art arrangement. In a conventional mobile acoustic reproducing apparatus, as shown in FIG. 1 (1), in a compartment 101, a right-channel loudspeaker sr is disposed at the front right position of a driver's seat 102, while a left-channel loudspeaker sl is disposed at the front left position of a side seat 103. These loudspeakers sl, sr are built in, for example, an instrument panel 104.
Therefore, referring to a driver 105, when sounds of equal energy level are released from the loudspeakers sl, sr, as shown in FIG. 1 (2), the acoustic energy distribution on the hearing sense of the driver 105 is not uniform between the left and right loudspeakers sl, sr, and it is deviated to the loudspeaker sr which is closer to the driver 105.
Accordingly, the localization position of a virtual sound source to be localized in the front direction of the driver 105 indicated by reference code l111 is deviated to the loudspeaker sr side as indicated by reference code 107. A similar problem occurs on the side seat 103.
In the limited space of the compartment 101, owing to the restrictions of the mounting positions of the loudspeaker sl, sr, the expansion angle indicated by reference code .theta.111 is smaller than 30 degrees capable of forming an ideal sound field.
In the mobile acoustic reproducing apparatus of the prior art, hence, the localization direction of the sound field is deviated to form an asymmetrical sound field, and an acoustic reproduction full of presence cannot be realized.